The present invention relates generally to devices and methods for perforating tubular structures and, more particularly but without limitation, to devices and methods for perforating well casings in subterranean wells to perform remedial operations such as testing and stimulation.
In the management of oil and gas wells, many procedures involve the movement of fluid or flowable material into or from a formation. During the drilling and production phases of a well, a testing procedure may be conducted to recover a sample of fluid from behind the casing to determine the quality or content of the fluid in the formation. Sometimes it is necessary to inject treatment fluids, such as acids, to stimulate or initiate production.
In one procedure called xe2x80x9csqueezing,xe2x80x9d cement is injected into the annulus around the outside of the casing to isolate a formation. This multi-operation procedure involves installing a bridge plug below the target area, perforating the casing, setting a squeeze tool above the target formation, and then pumping cement through the squeeze tool using a stinger. Thus, the conventional squeezing operation results in a short section of casing being left filled with cement, as well as the bridge plug and squeeze tool. All of this must then be cleared by re-drilling to reopen the well for production. In addition to being time-consuming and expensive, this conventional squeezing procedure is often ineffective.
In all of these procedures, the casing must be perforated and a flow path established between the surface and the perforation. The present invention provides a system, apparatus and method for perforating the well casing, establishing the fluid flow path from the perforation to the surface, and then plugging the perforation upon completion, all in one downhole operation which leaves the well casing unobstructed. However, the apparatus, system and method of this invention are versatile and have applications outside the oil and gas industry in tubular structures of various kinds.
The present invention is directed to an apparatus for perforating a tubular structure. The apparatus comprises a housing having a first end defining an inlet. The housing is supportable at a selected position in the tubular structure and defines an operating fluid flow path beginning with the inlet. Also included is a perforating assembly in the housing. The perforating assembly comprises a piercing member supported for movement from a first position within the housing to a second position in which a portion of the piercing member is extendable through the tubular structure. In addition, the piercing member comprises a fluid flow path. The perforating assembly defines a fluid flow path continuous with the operating fluid flow path through the housing and the fluid flow path in the piercing member. In this way, when the piercing member is in the second position, a continuous flow path is formed between the inlet of the housing and the portion of the piercing member that this extendable through the tubular structure. The apparatus also includes a control assembly adapted to control movement of the piercing member.
The present invention further comprises a perforating system for perforating the casing in a subterranean well. The system comprises a rotatable and axially movable elongate conduit sized to be received in the casing. The conduit has an end extendable into the casing. The system includes a perforating apparatus comprising a housing supportable at a selected position in the tubular structure. The housing has a first end defining an inlet, and the first end is connectable to the end of the conduit so that the conduit is continuous with the inlet. The housing defines an operating fluid flow path beginning with the inlet. The system includes a perforating assembly in the housing. The perforating assembly includes a piercing member supported for movement from a first position within the housing to a second position in which a portion of the piercing member is extendable beyond the housing to perforate the well casing. The piercing member comprises a fluid flow path. The perforating assembly defines a fluid flow path. continuous with the operating fluid flow path through the housing and the fluid flow path in the piercing member. Thus, when the piercing member is in the second position, a continuous flow path is formed between the conduit and the portion of the piercing member that is extendable through the well casing. A control assembly, adapted to control movement of the piercing member, is also included in this apparatus.
Still further, the present invention includes a valve for directing fluid from a source of pressurized fluid to one of a plurality of fluid-operated devices. The valve comprises a valve body having a tubular sidewall defining a longitudinal throughbore. The sidewall comprises a first inlet fluidly connectable to the fluid source, and a plurality of longitudinally spaced-apart outlets. Each of the plurality of outlets is connectable to a different one of the fluid-operated devices. A sleeve is sealingly slidable inside the throughbore of the valve body. The sleeve comprises an outer wall, an inner wall, and an annular space therebetween. A fluid inlet in the outer wall is in fluid communication with the annular space. Also, a plurality of outlets in the outer wall are in fluid communication with the annular space. Each one of the plurality of outlets corresponds to a respective one of the plurality of outlets in the valve body. The sleeve is axially movable from a closed position, in which none of the outlets in the sleeve is aligned with its corresponding outlet in the body, to a plurality of valving positions in which the inlet in the sleeve is aligned with the inlet in the valve body and in which one of the plurality of outlets in the valve body is aligned with the corresponding outlet in the sleeve. Thus, in each of the valving positions, fluid from fluid source is directed to the respective one of the fluid-operated devices.
In yet another aspect, the present invention is directed to a method for establishing a fluid flow path between one end of a tubular structure and a selected area outside the tubular structure a distance from the end. This method comprises perforating the tubular structure at a position near the selected area, and then flowing flowable material between the end of the tubular structure and the selected area outside the tubular structure without leaving a significant amount of the fluid inside the tubular structure.
In still another aspect, the present invention comprises an apparatus for perforating a tubular structure. The apparatus includes a housing having an inlet and an outlet. A fluid-driven piercing member is supported for movement from a first position within the housing to a second position in which a portion of the piercing member is extendable through the tubular structure. The piercing member comprises a fluid flow path. The housing defines an operating fluid flow path beginning with the inlet and connectable alternately with the fluid flow path in the piercing member and the outlet of the housing. A pressurized fluid reservoir is included, and is fluidly connected to the fluid driven piercing member. A first valve is adapted to control flow of fluid between the high-pressure fluid reservoir and the piercing member to drive the movement of the piercing member from the first position to the second position. A second valve is adapted to control flow of fluid between the operating flow path in the housing and to either of the flow path in the piercing member and the outlet of the housing.
Still further, the invention includes an apparatus for perforating a tubular structure. The apparatus comprises a housing, and a piercing member supported in the housing for movement from a first position to a second position in which a portion of the piercing member is extendable through the tubular structure. Also included is a fluid driven setting/pack-off assembly adapted to secure the apparatus temporarily at a selected position in the tubular structure. The setting/pack-off assembly comprises a back-up plate sized to engage the tubular structure. The back-up plate is movable in a first direction from a retracted position in which the back-up plate does not engage the tubular structure to an extended position in which the back-up plate engages the tubular structure. The back-up plate is also movable in a second direction from the extended position to the retracted position. The apparatus includes a pressurized fluid reservoir fluidly connected to the setting/pack-off assembly, and a valve adapted to control the flow of fluid from the fluid reservoir to the setting/pack-off assembly.